An often-overlooked precision maintenance tool is the V-belt tension gauge. Many maintenance technicians believe they can just go by “feeling” for what proper belt tension should be. In our Reliable Precision Maintenance (RPM) course, we often let mechanics tension the belts to what they “feel” is correct.  Then we check the tension with a V-belt tension gauge.  More times than not, we find that the belts are over-tensioned when going by “feel”.

Pros of Proper V-Belt Tension

Proper V-belt tension (along with precision alignment and proper ventilation) can dramatically increase the life of belts, sheaves, and bearings, reduce waste (from premature belt failure), minimize downtime, reduce excessive heat (from friction), and more.

Belts that run too loose cause excessive wear on the belts and sheaves.  Belts that are too tight can cause premature failure of the bearings.  Most industrial V-belting can have a break strength of several thousand pounds.  Excessive tension means the bearings are subjected to this excessive force as radial loading.

Different Types of Belt Tensioners

There are different types of belt tensioners, such as spring-loaded (see above photo) or sonic tools.  Regardless of the type you use, there are several things the installer needs to know:

• Horsepower
• Belt size
• Span between shaft centers
• Sheave diameters
• Deflection distance
• Deflection force

Most belt manufacturers publish these in their technical specifications.  In our training classes, we use the Browning Toolbox Technician© app to calculate the force and deflection values, and a simple spring-loaded gauge to set proper tension.

For more information, watch our video, How to Measure Belt Deflection.